I. Field
The present disclosure relates to vehicle wheel assemblies and valves for use with a central tire inflation system.
II. Background Information
Certain vehicles, such as those designed for some military applications, are required to travel over a variety of terrains. Because optimal tire pressure varies depending on the terrain, it may be desirable to adjust tire pressure during use. For example, when transitioning from an asphalt highway to a softer surface (e.g., sand, dirt, or snow), it is advisable to lower the vehicle's tire pressure in order to increase the tire's surface contact area, distributing the vehicle's weight over a larger area. However, in certain situations, it may be inconvenient or even dangerous (e.g., when the vehicle is deployed in combat situations) for the operator to exit the vehicle to manually adjust the tire pressure.
Central tire inflation (CTI) systems allow a vehicle's operator to adjust tire pressure without stopping or exiting the vehicle. A CTI system is a vehicle-mounted system that manages pressurized fluid and communicates it to the vehicle's tires. A typical CTI system may include a control switch/system (typically installed near the driver seat), an electronic control unit (ECU), a fluid delivery manifold, and CTI valves at each wheel position. Pressurized fluid may be communicated from a compressor mounted on the vehicle to the fluid delivery manifold via fluid lines. The control switch and ECU may activate valves in the manifold to deliver fluid under pressure via fluid lines mounted to or located within the vehicle body, frame, and axles through the hub to the CTI valves at the wheel positions. The CTI valves are often secured to the wheels on which the tires are mounted.
A CTI system transmits fluid from its source to the vehicle's tires through internal ducts in the wheels and/or wheel hubs, external conduits, or some combination thereof. Providing internal ducts inside the wheels and/or wheel hubs may offer certain advantages over external conduits. For example, external conduits may catch on something or be damaged in a variety of other ways. Given that CTI systems are often employed on vehicles used in rugged or dangerous environments, the risk to external conduits may be considerable. Thus, it is known in the art to provide ducts inside a wheel for communicating compressed air from a source to a wheel-mounted valve, and from the valve to a tire.
However, providing an internal duct through the wheel for communicating fluid between a CTI system and a valve also introduces potential difficulties. For example, the interface between the wheel's fluid duct and other components of the CTI system is susceptible to damage at various stages of the wheel's life (e.g., during manufacture, assembly, maintenance, or in use). If a wheel's CTI duct becomes damaged, that wheel must likely be discarded. Further, the interface between a wheel's CTI duct and the wheel is typically sealed using an o-ring or some other type of seal. These seals are also susceptible to damage or decay, which can result in fluid leaking at the interface between the wheel duct and the other components of the CTI system. It is also advantageous to make seals, conduits, and passages easily accessible for cleaning or replacement as needed to maintain the system. Wheels comprising a duct to carry fluid from a CTI system to a wheel-mounted valve may prevent or limit access to such seals, conduits, or passages when mounted on a wheel hub, making it necessary to remove the wheel to access the seals, conduits, and/or passages.